" Mucking with the network (e.g., turning temporary addresses off and on) gets the system to use a temporary address for a while, but check back in a few hours or the next day, and the permanent address the one being used. "ipconfig" shows multiple temporary IPv6 addresses available, but checking https://www.google.com/#q=what+is+my+ip in Edge, Chrome, and Firefox show the permanent address being used. "ping" can be convinced to use another address with the "-S", but otherwise it also selects the permanent address.

Having, but not using, temporary IPv6 addresses does not provide much in the way of privacy."

Yes, but you can easily plug it with a small amount of effort. Assuming your ISP is giving you an IPv4 address and not an IPv6 (in which case you are shit out of luck and need it) you can block all IPv6 traffic with several tweaks; each of which works on its own but you can bundle them all to make sure you are completely plugged.

Network Adapter
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Uncheck the IPv6 item under properties just for good measure.

Registry Hack
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1. Goto HKLM\SYSTEM\CurrentControlSet\services\TCPIP6\Parameters
2. Create DWORD (32-bit) value called "DisabledComponents" and set it to "FF"
3. Reboot and done

and if that is not paranoid enough for you, you can use your firewall to globally block: [::/0]

and that's that. All of which I have done on my system and there is zero IPv6 activity. Have fun.